1. Field of the Invention
The present invention relates to an electric dust collecting unit suitable for use in an air cleaner, a diesel-engine exhaust black-smoke removing apparatus, a factory oil-mist removing apparatus or a like.
2. Description of the Related Art
With an increasing degree of the air tightness of buildings such as offices, restaurants, recreational facilities, factories, housings or a like, in recent years, cigarette smoke, malodor, and other harmful substances suspended in air are becoming more and more likely to harm health of office workers or others and contaminate facilities and equipment. To guard against this, there has been widely used an electric dust collecting type of an air cleaner installed in offices or like for collecting and removing the malodor of cigarette smoke and suspended particles from indoor air. Of the air cleaners which may come in ceiling-embedded type, wall type, floor type, portable type, and high-table type ones, the high-table type air cleaner is described below as an example.
An air cleaner 5 shown in FIG. 11 and FIG. 12 with a smoking high-table is preferably installed in a waiting room of factories and a lobby of airports or hotels. This air cleaner 5 has an upper face of its own body as a table face 52 which an ashtray 51 or other items are put thereon, approximately at the center of which the table face 52 is provided a smoke intake opening 53. The apparatus body includes therein a pre-filter 54, a needle-discharge type electric dust-collecting unit 55, a deodorizing filter 56 made of active carbon fiber, a fan motor 57, and a power supply (not shown). Exit opening 58 for cleaned air is provided at a lower part on two sides of the apparatus body.
In operation, when the fan motor 57 draws in air containing cigarette smoke through the smoke intake opening 53, first most large smoke particles of thus drawn in cigarette smoke are trapped by the pre-filter 54. Next, small smoke particles are electrostatically collected by the electric dust-collecting unit 55 by corona electric charging. Finally, cigarette odor is absorbed and removed by the deodorizing filter 56. Thus cleaned air is then exhausted by the fan motor 57 again to a room through the exit opening 58 at the lower part. When the electric dust-collecting unit 55, the pre-filter 54, or the deodorizing filter 56 has become dirty, it is taken out through a pull-down type opening/closing door, to be cleaned, recovered, and then attached again for use.
As shown in FIGS. 13 and 14, the conventional electric dust-collecting unit 55 includes a male type sub-unit 6 which has an external-box type frame 61 in which many needle electrodes 63 are arrayed in a lattice against a plurality of rectangular longitudinal electrode supports 62 in a one-to-one relationship and a female type sub-unit 7 which has an internal-box type frame 71 in which many both-end-open angular cylinder shaped collector cells, collecting electrodes 72, are arrayed in a lattice, in such a configuration that both frame 61 and frame 71 are fitted to each other so that the collector cells 72 and the needle electrodes 63 (and the electrode supports 62) maybe correspondingly arranged in a one-to-one relationship, that is, into each of the collector cells 72, each of the needle electrodes 63 (and the electrode supports 62) may be inserted in a non-contact manner. Note here that both the male type sub-unit 6 and the female type sub-unit 7 are detachable for convenience in washing or other.
As shown in FIGS. 13 and 14 again, however, in the above-mentioned conventional electric dust-collecting unit, the needle electrodes 63 are each vertically long and as a whole arranged in parallel to an air flow path F, with their sharp needle tips facing a front opening, so that at a time of replacement or maintenance/inspection of the electric dust-collecting unit 55, a person in charge of work may be injured on his fingers or body by these needles.
In addition, since the prior art needle electrode support 62 is box shaped, it suffers a problem of a larger pressure loss due to a larger resistance against air flow.
In view of the above, it is an object of the present invention to provide an electric dust-collecting unit capable of performing replacement and maintenance/inspection of a dust-collecting unit thereof in safety and also of reducing pressure loss due to air flow.
According to a first aspect of the present invention, there is provided an electric dust-collecting unit including a plurality of needle electrodes each having a sharp needle tip for charging particles suspended in air by generating corona discharge around the sharp needle tip, collecting electrodes for electrostatically absorbing and collecting suspended particles charged by each the needle electrodes, and plate-shaped deflecting electrodes provided corresponding to the collecting electrodes, for giving the charged suspended particles deflecting force toward the collecting electrodes, in such a configuration that a air flow path for the air is formed between the collecting electrodes and the plate-shaped deflecting electrodes, wherein:
the collecting electrodes have a plurality of cross-sectional U-shaped electrode portions thereof arranged in parallel to each other in an overall cross-sectional comb-teeth shaped configuration; and
the plurality of needle electrodes is arranged corresponding to each of the U-shaped electrode portions constituting the collecting electrodes and each has the sharp needle tip thereof attached and fixed to a main face of the plate-shaped deflecting electrodes as projected into a cavity of a corresponding one of the U-shaped electrode portions of the collecting electrodes.
In the foregoing, a preferable mode is one wherein a first one of the collecting electrodes having a plurality of first U-shaped electrode portions and a second one of the collecting electrodes having a plurality of second U-shaped electrode portions are arranged facing each other with a predetermined distance provided therebetween and have the plate-shaped deflecting electrodes interposed between the first collecting electrode and second collecting electrode and also have the air flow path formed between the first collecting electrode and the deflecting electrode as well as between the second collecting electrode and the deflecting electrode;
first ones of the plurality of needle electrodes are arranged corresponding to each of the first U-shaped electrode portions of the first collecting electrode, in such a configuration that each of the first needle electrodes is attached and fixed to a first the main face of the deflecting electrode with the first sharp needle tip thereof as projected into the cavity of the corresponding one of the first U-shaped electrode portions; and
second ones of the plurality of needle electrodes are arranged corresponding to each of the second U-shaped electrode portions of the second collecting electrode, in such a configuration that each of the second needle electrodes is attached and fixed to a second the main face (opposite to the first main face) of the deflecting electrode with the sharp needle tip thereof as projected into the cavity of the corresponding one of the second U-shaped electrode portions.
Also, a preferable mode is one wherein the first main face or the second main face of the deflecting electrode has a needle-electrode mounting hole therein for mounting the needle electrode; and
each of the needle electrodes includes a needle portion and a body portion and is attached and fixed to the deflecting electrode with the body portion as tightly fitted into the needle-electrode mounting hole.
Also, a preferable mode is one wherein the first main face or the second main face of the deflecting electrode has a needle-electrode mounting hole therein for mounting the needle electrode; and
each the needle electrode includes a needle portion, a large-diameter body portion, and a small-diameter read-end step portion and is attached and fixed to the deflecting electrode with the small-diameter rear-end step portion as tightly fitted into the needle-electrode mounting hole.
Also, a preferable mode is one wherein the first main face or the second main face of the deflecting electrode has a plurality of needle-electrode mounting holes therein for mounting the plurality of needle electrodes; and
each the needle electrode includes a needle portion, a large-diameter body portion, and a small-diameter rear-end step portion and is attached and fixed to the deflecting electrode with the small-diameter rear-end step portion as inserted from a side of the main face of the deflecting electrode into a corresponding one of the needle-electrode mounting holes and caulked from a side of a face opposite to the main face.
Also, a preferable mode is one wherein the first main face or the second main face of the deflecting electrode has a needle-electrode mounting hole therein for mounting the needle electrode; and
the each needle electrode includes a needle portion, a large-diameter body portion, and a small-diameter rear-end step portion and is fixed by use of wax to the deflecting electrode with the small-diameter rear-end step portion as inserted into the needle-electrode mounting hole in the deflecting electrode.
Also, a preferable mode is one wherein the needle electrodes are each attached and fixed to the first main face or the second main face of the deflecting electrode with the sharp needle tip thereof as pointing to a desired position on the collecting electrode on an opposite-side.
Also, a preferable mode is one wherein the collecting electrodes and/or the deflecting electrodes are made of paper or synthetic resin which is coated with metal.
Furthermore, a preferable mode is one wherein the collecting electrodes and/or the deflecting electrodes are made of a stack of paper or synthetic resin and metal foil.
Also, according to a second aspect of the present, there is provided an electric dust-collecting unit including a plurality of needle electrodes each having a sharp needle tip for charging particles suspended in air by generating corona discharge around the sharp needle tips, collecting electrodes for electrostatically absorbing and collecting suspended particles charged by each the needle electrode, and deflecting electrodes provided corresponding to the collecting electrodes, for giving the charged suspended particles deflecting force toward the collecting electrodes, in such a configuration that an air flow path for the air is formed between the collecting electrodes and the deflecting electrodes, wherein:
the collecting electrodes have a plurality of cross-sectional U-shaped electrode portions thereof arranged in parallel to each other in an overall cross-sectional comb-teeth shaped configuration and the deflecting electrodes also have an overall cross-sectional comb-teeth shaped configuration;
each of the comb teeth of the deflecting electrodes is inserted into a corresponding one of the U-shaped electrode portions of the collecting electrodes in a spaced relationship therewith, thus alternately arraying each of the comb teeth of the collecting electrodes and each of the comb teeth of the deflecting electrodes; and
each the needle electrode is attached and fixed to the comb teeth of a corresponding one of the deflecting electrodes with the sharp needle tip thereof as projected into a cavity of an arbitrary one of the U-shaped electrodes constituting the collecting electrodes.
In the foregoing second aspect, a preferable mode is one wherein each the needle electrode has a groove portion in a rear-end face thereof and is attached and fixed to the deflecting electrode with the groove portion in the rear-end face as tightly fitted to a tip edge of the comb teeth of the corresponding one of the deflecting electrodes.
Also, a preferable mode is one wherein each the needle electrode includes a needle portion and a body portion and is attached and fixed to the deflecting electrode with a side of the body portion as adhered, in meeting contact, to the first main face or the second main face of the comb teeth of the corresponding one of the deflecting electrodes.
Also, a preferable mode is one wherein each the needle electrode is attached and fixed to the first main face or the second main face of the deflecting electrode with the sharp needle tip thereof as pointing to a desired position of the collecting electrode on an opposite side.
Also, a preferable mode is one wherein the collecting electrodes and/or the deflecting electrodes are made of paper or synthetic resin which is coated with metal.
Furthermore, a preferable mode is one wherein the collecting electrodes and/or the deflecting electrodes are made of a stack of paper or synthetic resin and metal foil.